Yeast is more than a little bit magic.
It is a living being imbued with the power to profoundly transform and create. It is a still-mysterious fungus that grows on fruit skins, cheeses, flowers, trees, and even our own bodies. So many of our favorite foods and drinks—sourdough, cheese, coffee, soy sauce, kombucha, wine and, of course, beer—wouldn’t exist without its quiet work. As Scientific American puts it, yeast is a lifestyle—and though that may be in reference to the makeup of its cells and how they reproduce, it’s also a rather wonderful description of all the ways that yeast touches, and even shapes, the course of our lives.
Rob Green and Mara Young, co-owners of Community Cultures Yeast Lab in San Antonio, Texas, know its power well. Their current facility, opened in 2020 and nestled among low clapboard houses in the historic Beacon Hill neighborhood, is unassuming, with no signage to indicate the extraordinary endeavors going on inside. In this simple, single-story building, the pair have isolated and propagated yeast sourced from native flora and fauna to offer the first “clean” foraged Texan brewing yeast.
That singular objective has driven them through years of uphill struggle. “For a long time, I barely slept more than three hours a night,” says Green. “We did huge amounts of multitasking on trips while still working our day jobs. On any one weekend we’d be picking up equipment, teaching classes, foraging for yeast, then back to work on Monday.”
This is my first visit to a yeast lab, and so I don’t know what to expect when Young opens the door, ushering me in out of the heavy Texas heat. I have come wearing Western boots after being scolded for my high heels on one too many brewery tours, but she greets me in sandals. Inside is a clean, bright atrium with coat hooks, visitor chairs, and a small kitchen. At first glance we could be in any office building: A large sunny conference room sits to my right, which is where, Young informs me with a smile, she writes all her emails to me.
As the two show me around, they detail the processes of foraging, extracting, cleaning, appraising, and propagating yeast, and most of all the desire to offer it up to brewers. “We asked ourselves: ‘Why are brewers attempting to make new styles of beer with only the traditional ingredients available to them?’” Green explains. “We set out to offer new yeast strains to experiment with, to push the envelope, to be creative, to perfect their craft, to express themselves as brewers, and to create an experience with their clientele that was truly unique and crafted from local ingredients.”
So, what’s so special about “clean” foraged yeast? Most foraged cultures contain “wild” Brettanomyces yeast and potentially contaminant bacteria, such as Lactobacillus or Pediococcus. These microorganisms are beloved among fans of spontaneous and mixed-fermentation beers for the complexity, sourness, and funk they impart. In contrast, what Green and Young offer is a locally sourced alternative to traditional brewer’s yeast, albeit with unique flavors and characteristics. Their strains are suitable for regular, non-sour beer styles, and enable Texan brewers to create everything from Pilsners and Hefeweizens to IPAs and Imperial Stouts, all with yeast sourced from within the state.
“Because our industry tends to use the word ‘wild’ in a very broad umbrella term for all things unwanted, it makes it very challenging to describe our indigenously sourced strains in a way that brewers can understand and appreciate,” Young says. “Our yeast is simply ‘beer yeast’ that did not come from another yeast manufacturer, did not come from a synthetic lab, and did not come from a brewery.”
Maybe because of a growing industry focus on local sourcing, sustainability, and the eco-footprint of brewing—or maybe because most Texans are boosters for their state—the unique work that Green and Young are doing has captured Lone Star State brewers’ attention.
Dorcol Distilling & Brewing Company in San Antonio is one among many Texan breweries excited to take up this new strain of localism. Head brewer Randy Ward and his co-owners Chris Mobley and Boyan Kalusevic used yeast that Community Cultures harvested from Big Bend National Park as part of a fundraising project to benefit Friends of Big Bend. “I’ve been going there since I was a child,” says Ward. “When I learned [Green and Young] had a yeast that came from the ocotillo plants in Big Bend, I knew I wanted to collaborate with them to make a beer using that yeast.” The result was a distinctive Black Saison, made with Weyermann Carafa Special 2 and Briess Midnight Wheat malts to get the dark color. “[It had] wonderful notes of pear, pepper, and clove,” Ward recalls.
The team at Nomadic Beerworks in Austin is proud of their strong environmental ethos and focus on sustainability, and discovering that they could brew with Texan yeast was a huge win, Nomadic’s co-founder Daniel Tyranski tells me. They used Community Cultures’ yeast in a blackberry sage Farmhouse Ale, made for the Texas Craft Brewers Guild’s Liquid Bake Sale fundraising initiative.
“This unique yeast [Chisos TCL32, harvested from the Chisos Mountains in Big Bend] was the perfect addition to our beer, which we saw as a celebration of Texas ingredients,” says Tyranski. “We needed a yeast that would pair well with the sweetness of the blackberry, while also working with the herbaceous quality of the sage we added. The flavor came through perfectly and the beer was a huge hit.”
Green and Young first met as undergraduates at San Antonio’s University of the Incarnate Word (UIW), where Green was specializing in microbiology, biochemistry, and genetics. Later, he worked in genetics and protein physiology at the University of Texas Health Science Center San Antonio, designing human protein production and isolation protocols by genetically transforming bacteria and yeast. In what spare time he had, he worked part-time at a local brewery—the now-shuttered Granary at The Pearl—and soon realized that he could apply his interest in yeast to a new discipline. Throw a love of hiking and camping into the mix, and all the ingredients were there for a unique approach to yeast sourcing and propagation.
Their outdoor adventures are where Young took the lead. “Rob hadn’t done a huge amount of camping,” she laughs. Their shared passion for nature not only brought them together as a couple, she says, but provided the key imperative for starting Community Cultures—a desire to actually taste the land itself. “Our original goal was to find and produce the terroir of Texas, through indigenously sourced yeast,” says Young. “We wanted to find something from Texas comparable to an English yeast, a Belgian yeast—to capture the flavor of Texas, of the southern USA.”
The process began with regular weekend camping trips, during which they traversed the state, collecting samples using homemade, shelf-stable kits before testing them in their garage. “The foraging is like Pokemon [GO] for yeast,” grins Green. “You don’t know what you’re going to find. [Like,] ‘Look at this fruit that’s splitting open with bubbles coming from it!’”
“Our original goal was to find and produce the terroir of Texas, through indigenously sourced yeast. We wanted to find something from Texas comparable to an English yeast, a Belgian yeast—to capture the flavor of Texas, of the southern USA.”
The analogy is perfect: I imagine the two of them trekking through the dusty outcrop of Big Bend National Park, eyes peeled for juicy specimens. “Big Bend was our first ‘official’ foraging trip—and it worked. It was a magical unicorn moment,” Young says. “Ocotillo TCL21 is still one of our most popular yeasts, and we had a great time. It was an adventure—we felt like we were going to fall out of the Jeep going up and down a nine-foot rock.”
Outdoor exploration is deeply entwined with the pair’s scientifically minded sense of discovery. Green tells me how they discovered a night-time balloon flower on a trip to the Grand Canyon. Sacred datura is highly poisonous, and has long been revered by local Native American tribes. “We were excited because it only blooms at night, and so you can only swab the inside of it at night without damaging the flower,” Young explains. “We were also intrigued as to what we might find inside of it, because yeast doesn’t survive in those hot desert temperatures, so to find something in the cool of the night was just a nifty concept.”
The two animatedly talk me through the drama of getting snowed in at the Grand Canyon’s North Rim, and how the temperature rocketed from 110 degrees Fahrenheit to sub-zero lows and back again. There is so much romance in their adventures that it’s easy to forget that this is, in fact, a business. Building the company while continuing the complex and experimental process of cultivating clean foraged yeasts has required a strategic approach: While its Texas yeast program is where Community Cultures has room to play, 95% of its revenue still comes from more traditional commercial yeast sales.
Young’s occupational experience was crucial in getting the business started. Prior to her role at Community Cultures, she worked in higher education as director of biology advising for UIW’s School of Math, Science and Engineering. “I got into that somewhat by accident,” she explains. “My educational background was in environmental theology, and I was looking for a way to transition back into that field.”
It was at that point that Green raised the idea of Community Cultures as a way to combine Young’s love of nature and her strong background in administration, business management, marketing, and website development. “Rob asked me if I would use my years in administration to help run the business, while also expanding my knowledge in sustainability to help direct the company in ways that would make us more environmentally responsible,” Young explains. It was the perfect fit.
Green’s rapid yeast identification system is crucial in establishing which of the hundreds of foraged yeasts that come into the lab will be suitable for brewing. We start our tour in the subculture room, where sterilization is a must. A negative-80-degree cryo freezer holds all the original culture samples, which are transferred to a sterile hood to be isolated. Green uses a flame-sterilized wire loop to pull out a microscopic piece of culture from the frozen cryo tube for propagation, while the machine blows sanitary air to preserve the sterile surface as he transfers the healthiest cells to grow in flasks.
I’m then introduced to the PCR (polymerase chain reaction) machine. This clever device rapidly multiplies DNA samples, which means that Green has sufficient quantities of any strain to perform his quality control tests. A process called gel electrophoresis is then used to separate the DNA according to fragment size, and enables Green to confirm the yeast’s genetic identification and characteristics—this tells him what qualities the yeast will bring to a beer.
“First we need to establish the yeast species,” Young explains. “We’re looking for Saccharomyces cerevisiae or pastorianus, although we also consider bayanus, which is traditionally a wine yeast.”
Once the species is established, the next task is discovering how it ferments, and the flavors it might impart—its sensory profile should realistically be suitable for beer, and it mustn’t over- or under-ferment. “This is often a problem,” Green concedes. “But there are still some discoverable yeasts that will work. All yeast strains came from the wild once.”
Other factors also come into play. “The presence of diastaticus … or a high POF [phenolic off-flavor] can be narrowing, as not all brewers want those flavors in their beer,” says Young. “These characteristics aren’t bad, but when you’re creating a yeast catalogue you are looking for the less common wild characteristics—then you know you have something to work with. Ideally we want it to be POF-negative, non-diastatic, cerevisiae-positive, at least 70% attenuation, and with good flavors.”
Next, Green hands me a petri dish. Each of its three segments contains a neat drizzle of yeast laid over a different colored substance. The first is malt extract agar, a control test for aerobic mold and a way to check for test reproducibility. The next compartment contains Wallerstein growth media, where the presence of contaminant wild yeasts is discovered. As Green is searching for clean, uncontaminated yeasts, the desired outcome of this test is for the yeast to drop the pH of the media, which will render it clear. Some yeast will absorb the color while others will metabolize it, making it possible to quickly discern different yeast strains and organisms. Any remaining non-yeast-like particles indicate contamination, making it unsuitable for propagation.
The final test in the dish is the Wallerstein differential media. The yeast is exposed to cycloheximide—a chemical that kills regular brewer’s yeast in small concentrations but not Brettanomyces. If there is any growth, Brett is present and the yeast is again unsuitable. “By one glance [at a single petri dish], you can say everything is alive and well and growing nicely and nothing is growing that’s not supposed to be growing,” Green says.
With his own rapid yeast identification system, Green has created a precise and thorough methodology that enables him to pinpoint the key characteristics of each yeast sample that he tests, including attenuation, flocculation, optimum fermentation temperature, and alcohol tolerance.
Once these factors are established and found acceptable, the final test is, of course, how the yeast tastes. Green’s lead lab technician, Dana De Hoyos, makes “beer shots” for testing—she grows small amounts of yeast cultures in autoclaved sanitized wort with a blow-off tube, as if brewing a beer in miniature, which she then pours into a glass to sample. This mini-beer showcases the yeast’s sensory characteristics, determining whether it will make the cut as a brewing yeast. The fridge is stocked with these miniature homebrew flasks, each fermenting a potential new addition to the catalogue—I wish I could prise them all open, and try them one by one.
There are currently 10 native yeast strains available on the Community Cultures website, but Green and Young have a backlog of over 550 samples that will take them several years to work through, despite the efficiency of Green’s rapid yeast identification system. Many of these samples have been sourced by “citizen scientists,” a project started back in 2017, when they were still working out of their garage.
“We realized that we can’t visit all the places they want to go,” Young says. “And we believe in a collective approach to accessing as much potential yeast as possible. Plus it’s hard to do field research while running a business.”
What initially started as a way for their friends to support Green and Young by bringing back yeast samples from their travels has blossomed into an international venture with fascinating vignettes attached to many of the samples.
“We found there are entire institutes in Japan with government funding to discover new native yeasts for sake,” Green says, failing to disguise his excitement. “People in New York have come to us looking for new strains for mead and sake, and there are people curating strains from fermented beverages and foods trying to reverse-engineer recipes, so they send us samples to discover what has gone into it. This guy went to Mexico looking for indigenous pulque and he traveled around villages looking for the original for us to replicate the yeast.”
Given increasing conversations about honoring culinary heritage and exploring local food production, it’s perhaps no surprise that this part of Community Cultures’ services has taken off. Fortunately, Green and Young are prepared: They provide a purpose-built, shelf-stable collection kit, which is sent to citizen scientists with return postage included.
“The kit changes color when you collect yeast, and its gas-exchange cap allows the pressure to change without exploding,” Green explains. “It needs to be sterile to preserve the yeast properly—it’s really complicated but it’s foolproof and it works.” The kits also come with forms declaring that the contents are safe and not a contaminant or pathogen. “You need FDA clearance to take anything foraged on a plane,” Green tells me, which I hadn’t realized.
Getting to this point was another labor of love. After approximately a year and four trial models, they finally nailed the design. “I could spend a day talking about how each one failed and the stuff I lost,” Green says wistfully. “There were a lot of exploding tubes, dead stuff, and rotting flowers,” Young concurs.
With so much interest and demand, Community Cultures is confronting a swift, vertiginous momentum, and the two are currently expanding their production facility to enable them to produce 40 times more yeast than their current output. “Most businesses are advertising for more business but we are the opposite,” Young says. “We don’t want to overextend or grow too fast, as we want to keep a really high level of customer service and quality.”
Still, they are looking forward to operating on a larger scale. “When we first started the business we really weren’t sure if anyone would be interested,” says Green. “So we bought a tiny system and tiny tanks, but we are now at capacity. It will be great to have more product on hand to meet demand faster and make sales immediately instead of breweries waiting a week for their yeast to be custom-made.”
From what the pair have observed, both brewers and drinkers are becoming savvier, and more curious, about yeast, which Green attributes to kveik’s popularity. “Every major distributor has kveik now—the trend started in about 2017 when we were just getting Community Cultures off the ground, and was definitely an indicator of how the industry was moving.”
Green and Young count a number of independent, pioneering yeast labs as their peers and inspirations. “The Yeast Bay in San Francisco are so good that one of the largest yeast labs in the world—White Labs—are now partnering with them to bring native yeast strains to the forefront,” Green says. “Bootleg Biology also have some really cool, interesting stuff—their mission is to get native yeast out to the people, and they’ve both been big inspirations to Community Cultures.”
“A ‘Belgian’ beer made in Texas is made with Belgian grains and a Belgian yeast strain that was once sourced from a Belgian brewery. We wanted our brewers to have the opportunity to both continue making traditional beers, but also challenge and inspire them to make ‘American’ beers, or new styles of beers, using genuinely American yeast strains sourced directly from the land.”
Riding the crest of this new way of thinking about yeast, and this new emphasis on local and native strains, is at the heart of what Community Cultures is offering to brewers. The company has created an opportunity for brewers in Texas and beyond to do something that’s both new and grounded in a tangible sense of place. Their mission is comparable to, but also apart from, previous generations of Wild Ale brewers who threw their doors open and allowed local microflora to inoculate their coolships of wort.
“A ‘Belgian’ beer made in Texas is made with Belgian grains and a Belgian yeast strain that was once sourced from a Belgian brewery,” explains Green. “We wanted our brewers to have the opportunity to both continue making traditional beers, but also challenge and inspire them to make ‘American’ beers, or new styles of beers, using genuinely American yeast strains sourced directly from the land.”
This is where Community Cultures offers a significant selling point for brewers. In an industry that’s always looking for something new—but which often finds itself working within the limiting strictures of just a handful of homogenous styles—these yeast strains, the unique flavors they impart, and the stories they tell have the potential to generate real innovation and new traditions.
At first, publicity around the couple’s venture was entirely word-of-mouth. Friends of friends, and eventually San Antonio homebrew clubs, started talking about these new, clean, locally foraged yeasts. Once Community Cultures officially launched, the Texas Craft Brewers Guild was swift to offer support.
“Mara and Rob have done a great job of getting plugged in with the Texas craft beer community through their involvement with the Texas Craft Brewers Guild and the connections they’ve forged with local brewers,” says Caroline Wallace, deputy director of the Guild. “Many breweries pride themselves on their Texas-made products, so I know these folks appreciate having the opportunity to get creative with Community Cultures’ unique native cultures collected from the Texas landscape and cultivated in their lab in San Antonio.”
Vista Brewing in Driftwood, Texas, is a farm-to-table brewery with a hyper-local ethos. Unsurprisingly, it has already brewed several beers with Community Cultures’ yeast, including Hive Mind Honey Ale, the yeast for which was harvested in a truly unusual way.
“Hive Mind is a project near and dear to me personally, as Vista’s beekeeper,” says Karen Killough, Vista’s co-founder. Green and Young’s sophisticated yeast-capturing enabled them to swab a sample of wild Saccharomyces from a moving honey bee inside the Vista apiary. This fortuitous interruption led to Hive Mind, which was brewed with honey donated by 25 Texas beekeepers, and which tasted “super dry and drinkable, with apricot, pear, and biscuit aromas and hints of honey, banana, and funnel cake,” as Killough describes it.
“This is a special beer because of [the] native yeast strain, and [the] businesses involved are Latino. The beer is a Farmhouse Ale called Yucatan Rain, brewed with Rocky Mountain juniper, ciruelas, and Yucatan yeast [Cenote Sac Actun, TCLJ1] from Community Cultures, as a tribute to Chaac, the Mayan rain god and protector of agriculture.”
“I have always wanted to do a collaboration with honey donated from that organization’s members,” says Killough. “Community Cultures helped take this to the next level by sourcing yeast from one of our bees.”
Even outside of the Lone Star State, brewers are getting in on the taste of Texan terroir. At Chicago’s Casa Humilde Cerveceria, co-founder Javier Lopez had his eye on Community Cultures’ work for a while. “I found out about Community Cultures back in my homebrewing days. I always knew I wanted to use them when we went pro,” he says. Lopez chose Community Cultures for a special collaboration project with Ørkenoy and Plant Shop. “This is a special beer because of [the] native yeast strain, and [the] businesses involved are Latino,” says Lopez. “The beer is a Farmhouse Ale called Yucatan Rain, brewed with Rocky Mountain juniper, ciruelas, and Yucatan yeast [Cenote Sac Actun, TCLJ1] from Community Cultures, as a tribute to Chaac, the Mayan rain god and protector of agriculture.”
In Wilmington, North Carolina, New Anthem Beer Project’s head brewer and general manager Aaron Skiles was keen to work with Community Cultures after trying a Jester King beer brewed with one of its native yeast strains. “We are always on the prowl for unique clean yeasts for our brewpub,” Skiles says. “We chose the Ocotillo strain; the descriptors were right up our alley. We brewed a Citra-dry-hopped Saison we hadn’t made in a couple of years called This Sick Beat.” Skiles underestimated the nuanced flavor the native culture offered. “I only wish I hadn’t had it dry-hopped so heavy-handedly. We should have been better about covering the beautiful and subtle fruit and spice.”
Daniel Tyranski of Nomadic Beerworks highlights the significance of Young and Green’s work for brewers like himself, who have a strong focus on sustainability. “Community Cultures is doing something really special for a couple of reasons,” he says. “First, they are discovering and isolating new strains of brewer’s yeast, which allow us to celebrate our local biodiversity with new flavors. Additionally, their work with more mainstream yeast varieties allows Texas breweries a closer option for sourcing standard types of brewer’s yeast.”
Now, with native strains in development from states including Arizona, Colorado, New Mexico, New York, and Massachusetts, and plans to cultivate clean foraged yeast from Mexico in the works, Community Cultures could soon be offering out-of-state, and even international, brewers a taste of their very own terroir.
While native yeast strains are what Community Cultures is best known for, they reflect only a small portion of its business. “Our native strains are a blessing and a curse,” explains Young. “Brewers who are scared of native strains will not order from us, as they think that’s all we do.”
“I’m worried about people pigeon-holing us,” adds Green. “So this is something we have to be very clear about.” Green and Young put an equal level of care and precision into their commercial yeast strains as they do with their foraged yeast. Commercial yeasts are sourced directly from the breweries best known for their use, or selected from world yeast banks. By choosing only the highest-performing yeast strains in each category with “the most delicious flavors” for their catalogue, Young and Green maintain their emphasis on quality and consistency.
Content analysis is another aspect of the business. “When a client gets their yeast pitch, there is a QR code for their yeast and it outlines everything they need to know,” says Green. “Our yeast is never more than a few weeks old versus months old. We also offer advanced customization—customers can mix-and-match any yeast strains for a truly unique mixed culture of their choosing.”
One of the ways in which they educate people about their work is through their online and in-person classes and workshops for breweries and homebrewers. Green and Young offer three types of class—quality control, flavor, and foraging—all of which help brewers to understand yeast better, and give them an opportunity to talk about their work.
“Lots of breweries want to understand what’s under the microscope when they look at yeast—we help them understand how to spot contamination and what to buy to stock their own yeast lab,” says Young.
During the pandemic, the classes, primarily led by Young, became virtual, but in-person workshops have now resumed, including foraging trips. “We teach people how to forage, where to go, how to use the [citizen scientist] kit, when to go, which are the best seasons—this is popular with homebrew clubs who will do a field trip together, also small breweries.”
Community Cultures is quite reasonably optimistic about the future. “Our goal is to be a full resource and support system for craft brewers, a ‘one stop shop’ for their yeast, of course, but also for consulting, classes and education, lab services and testing. We want to support the craft beer community in every way possible,” says Young. As the beer industry continues to become more experimental, and as brewers become keener to make their beer as place-centric as possible, Young and Green have timed their venture well.
“[Yeast] is the new frontier of what makes breweries unique,” says Green.
Words by Ruvani De SilvaPhotos by JoMando Cruz
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